Ok, my old eyes thought one was different. I am not certain there was a set in stone date for going to the bigger rids.
Sorta like everybody says the 340 for 1972 had a cast crank, when clearly there were both steel and cast. I think they used parts up as needed.
I do have two nice sets of the smaller lighter rods. Mopar Performance offered them for a time in match weighted sets with good rod bolts. They are still fairly sought after in some racing circles requiring stock rods, as they are much lighter than the later 340-360 style rod.
They were proven to be just as strong, too. Although that argument will rage on forever just like everything else.